Pipe nipples are commonly used as transition pieces in fluid systems of all types. In a basic form thereof, a pipe nipple is a short piece of pipe with each end adapted for connection to other components or other pipes within the fluid system. Pipe nipples are known for use in providing a threaded connection to an adjacent component and to provide an end area for connecting a hose or other flexible conduit to the nipple.
It is known to use pipe nipples in automobile cooling systems as a transition piece between cooling system components such as, for example, a water pump, and a hose conducting coolant to or from the pump. One end of the nipple has external threads thereon for threaded engagement with a threaded port on the pump, and the other end of the pipe nipple is adapted to receive a prepared end of the coolant hose. A ring clamp is used to secure the hose on the nipple. A portion of the nipple between the threads and the opposite end of the nipple is provided for external engagement by a tool used to turn the nipple and rotate the nipple threads into or out of the threads of the threaded pump port. The portion of the nipple engaged by the tool may be round or may have flattened faces, depending on the type of tool to be used for rotating the nipple. Known nipples of this type have been manufactured by machining processes.
Known automotive cooling system nipples have disadvantages and inadequacies. Manufacturing a cooling system nipple by screw machining or other similar cutting equipment inherently leaves grooves on all surfaces that are touched by the machine tool. Such grooves on the interior surface of the pipe nipple bore are problematic to some degree. A rough surface along which the coolant flows increases the friction co-efficient in the pipe nipple, which then tends to inhibit the flow of coolant through the nipple. Moreover, a rough surface promotes the accumulation of corrosive products, which not only may adversely affect the strength of the connector, but also further inhibit flow through the pipe nipple.
On relatively short nipples, as commonly found in automotive cooling systems, the external surface provided for driving or rotating the nipple is small. Thus, it is difficult to engage the nipple with the proper drive tool, and positioning the tool off the drive surface can damage the threads on one end of the nipple or damage the mating surface for the hose on the other end of the nipple. If driven with a common wrench, it is necessary to rotate the nipple a short distance, disengage, reposition and re-engage the wrench to rotate the nipple a further distance, continuing repetitively until the nipple is properly seated in the water pump or removed therefrom. This procedure can be time consuming. Further, the more times that the tool is disengaged from and re-engaged with the pipe nipple increases the possibility that the tool will be improperly positioned, causing the aforementioned damage or not properly seating to drive the nipple. U.S. application Ser. No. 10/460,127 filed Jun. 12, 2003 discloses a pipe nipple that can be driven in rotation by a tool inserted therein; however, aligning the tool for proper driving engagement can be difficult. The internal drive configuration of the nipple is at one end of the bore through the nipple. The drive tool must be axially aligned with the nipple as it approaches the end of the nipple, or the tool will not engage the drive configuration properly. In confined spaces this can be difficult.
To effectively seat the hose on the nipple in a fluid tight connection, the end of the hose is stretched somewhat to slide over the nipple. When the hose is applied over the nipple end, it is difficult to verify the length of the nipple portion within the hose. If an insufficient length of the nipple is in the hose, the ring clamp applied there around may not function effectively.
What is needed in the art is a pipe nipple formed by processes not using cutting tools on fluid contacting surfaces with a more effective drive configuration for the nipple that facilitates engagement by drive tools.